Thermosensitive recording media are ordinarily prepared by mixing together a colorless or pale-colored electron donating leuco dye (henceforth referred to as “leuco dye”) and an electron accepting color developing agent (henceforth referred to as “development agent”), such as a phenolic compound and the like, after grinding them into fine particles, preparing a coating solution by adding a binder, a filler, a sensitivity enhancing agent, a slipping agent and other aids to the mixture and applying the coating solution onto a substrate such as paper, synthetic paper, film, plastic and the like. Thermosensitive recording medium develops color through an instantaneous chemical reaction when heated using a thermal head, hot stamp, hot pen, laser light and the like and yields a recorded image. Thermosensitive recording media are used extensively in recording media such as facsimile devices, computer terminal printers, automatic ticket dispensers, recorders for meters, receipts at super markets and convenience stores and the like. Exceptional color development performance is sought in media that are used, for example, in handy terminal applications that are trending smaller, and high sensitivity, high resolution and excellent bar code readability are sought in label and ticket applications. Furthermore, opportunities to print advertisements and the like on the reverse media side are increasing when a thermosensitive recording medium is used as the recording medium for receipts and the like. Therefore, general printability (print through resistance, picking resistance during printing, ease of print processing and the like) is being sought in addition to qualities such as color development, sensitivity, image quality and the like that have previously been sought in thermosensitive recording media.
On the other hand, a low density paper containing fatty acid amides and the like is commonly known (Reference 1 etc.).
In addition, a thermosensitive recording medium with improved color development sensitivity prepared by lowering the thermal conductivity of the substrate by using a low density paper to which a non-ionic surfactant is added was disclosed (Reference 2). Thermosensitive recording media obtained using low density papers prepared by adding fatty acid amides, fatty acid esters and the like to the substrate were disclosed (References 3-5).